StrEdit is a minimalistic editor of the string table files that TES V: Skyrim plugins use to provide support for multiple languages. StrEdit can be used to create or update translations of string tables, without requiring their associated plugin to be present.

StrEdit does not contain any plugin localisation or delocalisation functionality, ie. you need to create the tables before StrEdit can be used to edit them. TES5Edit is recommended for doing that.

Forum thread here. Source code repository here.